Golgi apparatus, 3D computer reconstruction from electron microscope images. The Golgi apparatus is a complex of membranes and vesicles found in the cytoplasm of most eukaryotic cells. Its primary function is to modify, store and transport proteins and lipids made elsewhere in the cell. The organelle's structure consists of a stack of flattened, membranous, disc-like structures called cisternae. The cisternae contain enzymes that help to modify proteins passing through the organelle.